India Heat Reaches Dangerous Levels

India

by

Dan Satterfield

,

AGU Blogosphere

These are ground temperatures measured from the NASA Aqua satellite on Tuesday. They were over 50°C in NW India. Image: AGU Blogosphere

The dew-point reached 25-27°C [on June 7], and that is heat and humidity that almost no part of America has ever seen. This is deadly heat, even in the shade, and with this much moisture in the air, the temperatures do not drop at night, so there is little relief unless you have air conditioning, and many in India would consider that an unaffordable luxury.

Our bodies cool themselves with evaporational cooling, and when we sweat the moisture cools our skin as it evaporates. You can measure how much cooling you will get by placing a wetted cotton wick on the bulb of a thermometer, then swinging it for about 45 seconds, and looking at the temperature. This is the WET BULB temperature, and from it you can derive the dew point and the relative humidity. Think about this though, if the wet bulb gets much above 90°F degrees your body is going to get very little cooling, and it will start to heat up. The wet bulb was certainly near or above 30°C (86°F) today on parts of India, and this is approaching the level of deadly heat.

Now, think about this… If India warms like the rest of the land masses over the next several decades, then it is very possible, we will start to see wet bulbs over 32°C before the summer monsoon arrives.